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Chlorophyll and carotenoids: pigments of photosynthetic biomembranes. Meth Enzymol

Methods in enzymology (Impact Factor: 2.19). 01/1987; 148C:350-382. DOI: 10.1016/0076-6879(87)48036-1
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    • "2.2. Methods Total chlorophylls (Chl aþb) and carotenoid contents (Car xþc) were estimated spectrophotometrically (UV/VIS 550, Unicam, UK) from pigment extracts in 80% acetone (Lichtenthaler, 1987 "
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    ABSTRACT: We examined the acclimation response of the photosynthetic apparatus of barley (Hordeum vulgare L.) to a combination of UV-A and UV-B radiation (UVAB) and to UV-B radiation alone. Our aim was to evaluate whether UV-A radiation prevents UV-B-induced damage to the photosynthetic apparatus and whether UV-A pre-acclimation is required to mitigate the negative influence of UV-B radiation. Barley plants were grown from seeds under low photosynthetically active radiation (50 μmol m(-2) s(-1)) either in the absence or presence of UV-A radiation (UVA- and UVA+ plants, respectively). After 8 days of development, plants were exposed simultaneously to UV-A and UV-B radiation for the next 6 days. Additionally, UVA- plants were exposed to UV-B radiation alone. The UVA+ plants had a higher CO2 assimilation rate near the light-saturation region (AN) and a higher content of both total chlorophylls (Chls) and total carotenoids than the UVA- plants. Chls content, AN, the potential quantum yield of photosystem II (PSII) photochemistry (FV/FM), the capacity of light-induced thermal energy dissipation and the efficiency of excitation energy transfer within PSII remained the same or even increased in both UVA+ and UVA- plants after UVAB treatment. On the contrary, exposure of UVA- plants to UV-B radiation itself led to a reduction in all these characteristics. We revealed that the presence of UV-A radiation during UVAB treatment not only mitigated but completely eliminated the negative effect of UV-B radiation on the functioning of the photosynthetic apparatus and that UV-A pre-acclimation was not crucial for development of this UV-A-induced resistance against UV-B irradiation. Copyright © 2015 Elsevier Masson SAS. All rights reserved.
    Plant Physiology and Biochemistry 11/2015; 96:90-96. DOI:10.1016/j.plaphy.2015.07.017 · 2.35 Impact Factor
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    • "Absorbance of the supernatant was measured at 663.2 nm, 646.8 nm and 470 nm. The concentrations were calculated according to Lichtenthaler (1987). For measuring the fluorescence from photosystem II, the plants were dark-adapted for 30 min. "
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    ABSTRACT: Cobalt (Co(2+)) inhibits vegetative growth of Lemna minor gradually from 1μM to 100μM. Fronds accumulated up to 21mgCo(2+)g(-)(1) dry weight at 10μM external Co(2+) indicating hyperaccumulation. Interestingly, accumulation of Co(2+) did not decrease the iron (Fe) content in fronds, highlighting L. minor as a suitable system for studying effects of Co(2+) undisturbed by Fe deficiency symptoms unlike most other plants. Digital image analysis revealed the size distribution of fronds after Co(2+) treatment and also a reduction in pigmentation of newly formed daughter fronds unlike the mother fronds during the 7-day treatment. Neither chlorophyll nor photosystem II fluorescence changed significantly during the initial 4d, indicating effective photosynthesis. During the later phase of the 7-day treatment, however, chlorophyll content and photosynthetic efficiency decreased in the Co(2+)-treated daughter fronds, indicating that Co(2+) inhibits the biosynthesis of chlorophyll rather than leading to the destruction of pre-existing pigment molecules. In addition, during the first 4d of Co(2+) treatment starch accumulated in the fronds and led to the transition of chloroplasts to chloro-amyloplasts and amylo-chloroplasts, while starch levels strongly decreased thereafter. Copyright © 2015 Elsevier Ltd. All rights reserved.
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    • "Light absorbance at 663, 644 and 452.5 nm was measured by spectrophotometer (Halo DB-20/ DB-20S, Dynamica Company, London, UK) (Metzner et al. 1965). The concentrations of chlorophylls and carotenoids were calculated by using the adjusted extinction coefficients and equations (Lichtenthaler 1987). "
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